5 Answers
5

Advantages: novelty. That's about it. It's hard to keep it on the table when you roll it, and it's super-hard to read it, because you can't always tell which facet is the highest. It's a cute conversation piece but it's not really useful at all in play.

The d100 is a golf ball. It never stops and it's very large, hence it fits badly into a pencil bag. However, it has a definitive coolness factor. I saw one with water and a bubble inside, making reading much easier, but it becomes very heavy, and a nightmare if it breaks.

I can't see any use for the d100 other than as a novelty item, such as the large d20s. Their design obviously lends them to extra-long rolls and mistaken interpretation. Also, I've yet to see need for this type of roll in 4th Ed. Of course, YMMV in other systems.